Structural units of gridlike construction providing supports for walls, floors, or the like



Dec. 19, 1950 A. M. BUTI'S 2,534,852

smucwum. UNITS 0F GRID-LIKE cous'mucnou PROVIDING SUPPORTS FOR A. M. BUTTS 2,534,852 CTION PROVIDING THE LIKE Dec. 19,

0F GRID-LIKE CONSTRU FOR WALLS, FLOORS OR STRUCTURAL UNITS SUPPORTS Filed Sept. 12, 1945 8 Sheets-Sheet 2 FVQVA/Q/O/Q/Q vii $2 222:

IINP/Ill' STRUCTURAL um'rs 0F SUPPORT Sept. 12, 1945 Dec. 19, 1950 Dec. 19, 1950 A. M. BUTTS ,852

smuc'ruw. um 0F GRID-LIKE CONSTRUCT PROVIDING SUPPOR s FOR WALLS, FLOORS OR was IKE Film Sept. 12, 1945 a Sheets-Sheet 4 A. M. BUTI'S "2,334,852 smucm um'rs 0F GRID-LIKE cous'mucuou vnovmmc Dec 19, 1950 SUPPORTS FOR WALLS, FLOORS OR THE LIKE 8 Sheets-Sheet 5 Filed Sept. 12, 1945 in, o m a j E 7! I E\A mill... llll Dec 19, 1950 A. M. BUTTS 2,534,852

STRUCTURAL UNITS OF GRID-LIKE CONSTRUCTION PROVIDING SUPPORTS FOR WALLS, FLOORS OR THE LIKE Film Sept. 12, 1945 8 Sheets-Sheet 6 u? rzaey Dec. 19, 1950 A. M. BUTTS 2,534,852

STRUCTURAL UNITS 0F GRID-LIKE cousmucnou pnovxnmc SUPPORTS FOR WALLS, FLOORS 0R ms LIKE 8 Sheets-Sheet 7 Filed Sept. 12, 1945 Patented Dec. 19, 1950 STRUCTURAL UNITS OF GRIDLIKE CON- STRUCTION PROVIDING SUPPORTS FOR WALLS, FLOORS, OR THE LIKE Alfred M. Butts, New York, N. Y. Application September 12, 1945, Serial No; 615,741

11 Claims. I

This invention relates to load-supporting structural units of novel construction.

One object of the present invention is to provide a novelassemblage of structurally strong elements so interconnected as to form an eflicient load-supporting structure.

Another object is to provide a load-supporting structure of the above character which is adapted to spread a load applied thereto substantially uniformly throughout its members.

A further object of the invention is to provide a. novel load-supporting structure comprising a plurality of elements of standard construction which are adapted for prefabrication and from which said structure may be readily and rapidly assembled at the site of use.

A still further object is to provide a novel assemblage of structural elements interconnected in a novel manner whereby each element serves to support the ends of at least one other element and has at least one of its ends supported intermediate the endsof a third element.

A still further object is to provide a novel load-supporting structure comprising a plurality of elements of standard construction wherein said elements are connected to form a grid adapted to span a predetermined area.

Still another object is to provide a novel construction of the above character wherein one or more structural elements may be readily added to the assemblage to provide a panel for spanning diiferently shaped areas or distances of differing lengths.

A still further object is to provide a novel structural assemblage comprising a plurality of structural units wherein said units are pivotally connected in a novel manner to permit folding of said assemblage so that said units are pressed together into a minimum area.

A further object is to provide a novel construction of the above type in the form of a ver tical panel comprising struts and connectors to said struts wherein the entire panel, in its ex."- panded position, acts in a single unit to support a vertical force applied to the panel.

These and other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises an article of manufacture possessing the features, properties and relation of elements which will be exemplified in the articles hereinafter described and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the accompanying drawings, wherein:

Figure 1 is a perspective view, with parts broken away, of one novel assemblage of truss Still another object of the invention is to provide a novel construction in the form of a structurally strong grid wherein the elements comprising the grid are trusses of standard size connected to one another by connecting means of simple construction, said grid being adapted to provide an efiicient structure for supporting the floor or roof, for example, of a building.

A further object of the invention is to provide a structural assemblage comprising standardized, prefabricated truss units arranged to form a cross-cross, four-way pattern for spanning a predetermined area of a building, said assemblage being adapted to spread a load applied in a vertical or an angular direction across the entire area without undue concentration.

A still further object of the invention is to provide a novel load-supporting structure comprising a plurality of structural units interconnected in a novel manner so that said structure may be collapsed or folded into a relatively compact pattern, saving space and expense in manufacturing, storing and shipping.

Still another object is to provide a structural assembly of the above type which gives a construction stronger than that resulting from conventional load-supporting units.

elements comprehended by the present invention;

Fig. 2 is an exploded perspective view of a portion of the structure of Fig. 1 showing the construction of the elements constituting the assemblage and the construction of the means for connecting together said elements;

Fig. 3 is a top plan view of a floor-supporting structure formed from the truss assembly of Fig. 1 supported on the four walls of a rectangular building;

Fig. 4 is a top plan view of a modified assemblage of the truss elements of Fig. 2 whereby a compact structure suitable for resisting concentrated loads and/or for spanning a distance between two points is obtained, said structure being useful also for compactly assembling the truss elements for shipping;

Fig. 5 is a perspective view of a novel assemblage of structural elements providing a loadsupporting structure particularly adapted for use in a vertical position, said elements being pivotally connected to render said structure collapsible so that it occupies a relatively small area in relation to the area it spans in expanded position;

Fig. 6 is a view similar to Fig. 5 showing the assemblage of Fig. 5 in collapsed position;

Fig. 7 is a fragmentary, perspective view, with parts broken away, showing a pair of the structural elements of the structure of Fig. 5 and the connector member therefor;

Fig. 8 is a fragmentary, top plan view showing the structure of Fig. 7 operatively mounted 3 in another structural element it appears in collapsed position;

Fig, 9 is a fragmentary, top plan view showing the structure of Fig. 8 in expanded position;

Fig. 10 is a perspective view of a modification of a segment of a collapsible structural panel embodying the present invention wherein the structural elements are beams, and a construction suitable for use as a horizontal panel is obtained;

Fig. 11 is a fragmentary, exploded, perspective view showing the construction of the ends of the beams of the structure of Fig. 10 and the connector member therefor;

Fig. 12 is a fragmentary, top plan view of the structure of Fig. 10 showing one of the connectors operatively connected to the three panels normally associated therewith, the structure being shown in collapsed position;

Fig. 13 is a view similar to Fig. 12 showing the structure in expanded position;

Fig. 14 is a perspective view of another embodiment of the load-supporting structure of the invention wherein a collapsible assemblage is obtained from structural elements which are trusses:

Fig. 15 is an exploded. perspective View of three of the truss elements and one connector plate of the structure of Fig. 14; and

Fig. 16 is an exploded, perspective View showing a truss element of the character employed in the embodiment of Figs. 1 and 2 and the connectors which are adapted to render an assemblage formed of said truss elements collapsible.

One form of the present invention comprehends a novel construction comprising structur ally strong elements connected in a novel manner to provide a pattern for spanning a predetermined vertical, sloping or horizontal area, said construction being adapted to provide an efiicient support for loads applied in the plane of or at an angle to the plane of said area. Where the structure is intended to span a horizontal or sloping area and provide a support for loads which are applied principally in a direction perpendicular to the area which is spanned by the structure, as for example where the construction is intended to support the roofs or the floors of a building, it is preferable to use structural units in the form of trusses which are interconnected so as to lie in planes perpendicular to the plane of the area which the composite structure spans. One such construction is shown by way of illustration in Figs. 1 through i in the form of a framework for supporting the flooring, for example, of a building having a substantially rectangular foundation (Fig. 3).

Referring particularly to Figs. 1 and 3, the loadsupporting structure comprises a plurality of truss-like structural units 32 of the same size and shape providing a plurality of substantially parallel rows 34 which extend across the area spanned, each row comprising a plurality of said structural units connected end to end, the end element of certain of the rows consisting of only a longitudinal portion of one of said units, as shown for example at 38. A plurality of rows 38 of said units 32 extend parallel to one another in a direction substantially perpendicular to the rows 34, rows 38 being also provided in some cases at their ends with only portions of said units, as shown for example at 40. It is to be understood that the portions 40 may, if desired, be increased in length to accommodate the pattern of the load-supporting structure to shapes which may be somewhat irregular and to sizes to which the predetermined unit length of the elements 32 may be otherwise poorly adapted. Moreover, the structure may be advantageously employed, if desired, with its rows 34, 38 positioned at angles other than degrees to the walls of the building construction spanned thereby.

In order to form this novel criss-cross or gridlike pattern from elements 32, while at the same time obtaining an efiicient load-supporting structure which is adapted to spread loads applied thereto, said elements are constructed and interconnected in a novel manner. Each of said elements is provided intermediate its ends, preferably at the center thereof, with means for supporting the ends of two other of said elements, as, for example, by being provided with a pair of slots or openings 42, best shown in Fig. 2. Each of said openings is adapted to receive a suitable connector 44 such as a rectangular block, which is secured to the walls of said opening and has the ends thereof projecting on opposite faces of the element. Projecting ends may also be provided by other means, such as angle pieces firmly attached to each face of said element without passing through the element. Each of connectors 44 is adapted to engage and support the ends of two of elements 32, one on each side of the element centrally supporting said connectors, said connectors extending into recesses 46 provided therefor at the ends of said elements. As a result of this construction, the end of each of elements 32 is connected at two points to the center of another of said elements by means of said connectors, producing a structure wherein each of the elements supports two others of said elements at its center and has its ends supported by the centers of another pair of the elements. This interconnection of the members ties all together, so that the entire structure acts as a unit in supporting loads applied thereto.

It is also possible to use the novel truss units described above to build up an extremely compact load-supporting structure of substantially any weight and dimension capable of spanning the distance between two points and supporting loads applied between said points. A construction of this type is shown by way of example in Fig. 4 and is obtained by arranging elements 32 in parallel rows in substantially face-to-face engagement. The ends of the elements of each row are disposed opposite the centers of the units of the adjacent rows whereby a plurality of connectors 48 may be used to interconnect the centers of the units of alternate rows to the ends of the units of the rows adjacent to said alternate rows.

This construction also results in a unified truss system in that each truss element is supported at each end by the center of another element, the connectors binding the elements together into a unitary structure. It will be readil appreciated that the above arrangement of the elements provides an extremely compact structure and may be utilized for shipping the units after prefabrication to the point of assembly where they may be dismantled and reassembled to provide a structure of the type shown in Fig. 1.

The novel criss-cross or grid arrangement of structural elements described above, wherein each element supports intermediate its ends two other elements and has its ends supported, in turn, intermediate the ends of still other elements, may be utilized to form a vertical load-supporting structure. 1. e. a supporting structure which is adapted to be used principally in a vertical plane, for example as a wall or as the side of a bridge. An example of a novel construction of this character is shown in Figs. 5 through 9 and embodies an additional novel feature in that it is collapsible and may be shipped to the site of use in extremely compact form. As shown, each of the structural elements of said construction is a strut 50 comprising a pair of rectangular beams 52 formed, for example, of plywood and spaced in a direction perpendicular to the plane of the panel a distance equal to the thickness of connectors 54. Each of said connectors is centrally mounted between said beams by a suitable pivot 56 as, for example, the shank of a bolt. The ends of two of said struts are rigidly secured to each connector, as shown in Fig. 7, so that said members are parallel with one another but are spaced apart, in a direction perpendicular to their lengths, a distance substantially equal to or slightly greater than the width of each of said struts (Fig. 8). The ends of said struts are also substantially parallel with one another and are separated a distance approximately equal to the Width of the strut (Fig. 9). Accordingly, in expanded position, as shown in Fig. 9, the strut ends abut the side of the strut which mounts the connector and which constitutes the support for said ends. On the other hand, in collapsed position, as shown in Fig. 8, the side of the struts whose ends are secured to the connector plate abut the sides of the strut which mounts the connector plate so that in collapsed position a minimum space is occupied by the structure, as shown in Fig. 6. As a result of this construction, standardized units of substantially any material may be joined in the shop in the folded position, stored folded if desired, and then, when necessary, transported in folded position to the site of use, and expanded only when placed in operative position ready for use at said site. The structure; therefore, lends itself to quantity production on a continuing rather than seasonal basis, and saves space and expense in manufacturing, storin and shipping.

It is important to note that the rotation of the elements into expanded position causes the ends of each strut to abut the sides of other struts, producing a panel which acts as a single unit to support loads applied in a vertical direction as, for example, in a direction indicated by arrows 58 (Fig. 5) and giving the panel great strength. By virtue of this arrangement, the vertical load is substantially equally distributed throughout the various struts, producing in effect a truss action.

It is also important ,to note that the above described structure can be increased in either length or width or both by adding struts, connectors and pivots of the same size. In this way, standardized short units can be used to make a wall or truss of any dimension. The butting action which is produced by rotation of the elements into expanded position will always exist throughout the structure, regardless of the size of the struts, giving a unified truss action across the entire panel.

A modification of the above structure, wherein a collapsible assemblage is obtained, is shown in Figs. 10 through 13, and comprises structural members in the form of relatively simple beams 60, said beams being so arranged that the structure may be used, for example, as the support for a floor or roof, i. e. in a horizontal or sloping plane, as well as in a vertical plane. As shown, each said beam is rectangular in shape and has a bifurcated end 62 (Fig. 11) and the center thereof is provided with a recess 64 whose sides 66 (Fig. 12) extend obliquely to the sides of the beam and are parallel with one another. A connector 68 formed, for example, of plywood, is adapted to be pivotally mounted within each of recesses 64 as by a pivot I0, said connector preferably comprising a central portion .12 and end portions 14, each end portion being adapted to extend within the bifurcated end of the beam which it supports. The width of central portion 12 of each connector is substantially equal to the width of the beam, and in expanded position, as shown in Fig. 13, the ends of said central portion of the connector are adapted to engage and. abut the side walls 66 of recess 64. Moreover, the ends 62 of beams 60 are adapted to abut the sides of the strut to which they are connected. As a result of this dual abutting action, the panel will resist loads applied perpendicularly to, as well as in the plane thereof, and as a result of the interlocking arrangement far greater rigidity and strength are obtained than by the use of a conventional beam arrangement of equal weight.

It is to be understood that the novel collapsible arrangement of structural elements shown in the two embodiments of Figs. 5 and 10, respectively, may be embodied in an arrangement of the type shown in Fig. 1 wherein the structural elements are trusses whose principal planes lie in a direction perpendicular to the plane of the area spanned by the structural unit.

One form of construction of this type is shown in Figs. 14 and 15 as comprising a plurality of truss elements of the inverted Warren type, whereby a single connector 82 pivotally mounted in a slot 84 in the center of each truss element supports the ends of two other of said truss elements, as shown in Fig. 15.

It is also possible to form a collapsible structure from the truss elements 32 of the embodiments illustrated in Figs. 1 and 2 as, for example,

by providing a pair of connectors which are pivotally mounted in recesses 42 at the centers of said elements. Connectors 90 (Fig. 16) are adapted to support the ends of each of two of truss elements 32 at two points so that said truss elements are parallel with one another but are spaced a distance substantially equal to the thickness of said elements. The ends of said elements are also spaced a distance substantially equal to said thickness. This produces a collapsible structure which, in collapsed condition, results in a construction at least as compact as that shown in Fig. 4. As pointed out above, this type of panel can be used to span any area. Moreover, the openness of the truss frames permits easy passage of pipes, conduits, ducts, etc. through all parts of the structure.

There is thus provided a novel arrangement of structural elements whereby said elements are interconnected to form a, criss-cross or grid pattern for spanning a predetermined vertical, horizontal, or sloping area. The structural elements may be trusses or beams of novel construction adapting the structure for utility as a floor support. Furthermore, the novel load-supporting structure of the present invention may be formed in a novel manner so that the entire structure may be folded into a relatively small area, facilitating manufacture, storage and shipment thereof. In every instance, the structure may be formed of structural elements of substantially the same size and shape or parts thereof and connectors of substantially the same size and shape secured to said structural elements by means or substantially any standard type of connection, providing a rigid connection in one instance, and a pivotal connection in another instance. The structures are particularl useful for buildings, bridges and docks, andmay also provide panels for portable structures, removable partitions, gates, nets, racks and reinforced rod rids.

Since certain changes may be made in the above articles and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in th accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A load-supporting grid comprising at least four structurally strong elements of substantially uniform construction interchangeable with one another and at least four connector members appreciably shorter in length than said elements and of substantially uniform construction, said connector members also being interchangeable with one another, each connector member being mounted intermediate the ends of one of said elements and being supported by said element so that its ends extend on opposite sides of said element and each of said elements having one end thereof secured to one end of one of said connector members to form a structural pattern whose center is a closed, four-sided figure having its sides of equal length and formed by a portion of the length of each of said four elements, a connector member being located at each 'corner of said four-sided figure and a portion of each element extending for a substantial part of its length as a projection of each side of said foursided figure, one end of each of said connector members and of said elements being thus available for further connection with other structurally strong elements and connector members of similar construction to continue the foregoing structural pattern and to produce a grid covering substantially any desired area.

2. A load-supporting grid comprising at least four structurally strong trusses of substantially uniform construction interchangeable with one another and at least four connector members appreciably shorter in length than said trusses and of substantially uniform construction, said connector members also being interchangeable with one another, each connector member being mounted intermediate the ends of one of said trusses and being supported by said truss so that its ends extend on opposite sides of said truss and each of said trusses having one end thereof secured to one end of one of said connector members to form a structural pattern whose center is a closed, four-sided figure having its sides of equal length and formed by a portion of the length of each of said four trusses, a connector member being located at each corner of said four-sided figure and a portion of each truss extending for a substantial part of its length as a projection of each side of said four-sided figure, one end of each of said connector members and of said trusses being thus available for further connection with other structurally strong trusses and connector members of similar construction.

to continue the foregoing structural pattern and to produce a grid covering substantially any desired area.

3. A load-supporting grid comprising at least four structurally strong trusses of substantially 8 uniform construction interchangeable with each other and at least four pairs of connector members, each of said connector members being appreciably shorter in length than said trusses and of substantially uniform construction, said connector members also being interchangeable with one another, each pair of connector members being mounted intermediate the ends of one of said trusses and being supported by said truss so that their ends extend on opposite sides of said truss and each of said trusses having one end thereof secured to one end of a pair of said connector members to form a structural pattern whose center is a closed, four-sided figure having its sides of equal length and formed by a portion of the length of each of said trusses, a pair of connector members being located at each corner of said four-sided figure and a portion of each truss extending for a substantial part of its length as a projection of each side of said foursided figure, one end of each pair of said connector members and of said trusses being available for further connection with other trusses and connector members of similar construction to continue the foregoing structural pattern and to produce a grid covering substantially any desired area.

4. A load-supporting grid comprising at least four structurally strong trusses of substantially uniform construction interchangeable with one another and at least four connector members appreciably shorter in length than said trusses and of substantially uniform construction, said connector members also being interchangeable with one another, each connector member being mounted intermediate the ends of one of said trusses and being supported by said truss so that its ends extend on opposite sides of said truss and each of said trusses having one end thereof secured to one end of one of said connector members to form a structural pattern whose center is a closed, four-sided figure having its sides of equal length and formed by a portion of the length of each of said four trusses, a connector member being located at each corner of said four-sided figure and a portion of each truss extending for a substantial part of its length as a projection of each side of said four-sided figure, one end of each of said connector members and of said trusses being thus available for further connection with other structurally strong trusses and connector members of similar construction to continue the foregoing structural pattern and to produce a grid covering substantially any desired area, one surface of each of said trusses lying in approximately the same plane as the corresponding surface of each of the other trusses, the structure being thus adapted to directly receive a suitable fiat covering for the area spanned thereby, the principal planar dimension of said trusses being substantially perpendicular to the plane of the area spanned by said structure.

5. A load-supporting grid comprising at least four structurally strong elements of substantially uniform construction interchangeable with one another and at least four connector members appreciably shorter in length than said elements and of substantially uniform construction, said connector members also being interchangeable with one another, each connector member being mounted intermediate the ends of one of said elements and being supported by said element so that its ends extend on opposite sides of said element and each of said elements having one end thereof secured to one end of one of said connector members to form a structural pattern whose center is a closed, four-sided figure having its sides of equal length and formed by a portion of the length of each of said four elements, a connector member being located at each corner of said four-sided figure and a portion of each element extending for a substantial part of its length as a projection of each side of said foursided figure, one end of each of said connector members and of said elements being thus available for further connection with other structurally strong elements and connector members of similar construction to continue the foregoing structural pattern and to produce a grid covering substantially any desired area, each said element comprising a pair of beams spaced depthwise to provide a space for mounting the connector members associated with said element.

6. As a new article of manufacture, a collapsible load-supporting structure forming, in expanded position, a structurally strong grid for spanning a predetermined area, said structure comprising at least four structurally strong elements of substantially uniform construction interchangeable with one another and at least four connector members appreciably shorter inlength than said elements and of substantially uniform construction, said connector members also being 1 interchangeable with one another, each connector member being pivotally mounted intermediate the ends of one of said elements and being supported by said element so that its ends extend on opposite sides of said element and each of said elements having one end thereof secured to one end of one of said connecto members to form in expanded position a structural pattern whose center is a closed, four-sided figure having its sides of equal length and formed by a portion of the length of each of said four elements, a connector member being located at each corner of said four-sided figure and a portion of each element extending for a substantial part of its length as a projection of each side of said foursided figure, one end of each of said connector members and of said elements being thus available for further connection with other structurally strong elements and connector members of similar construction to continue the foregoing structural pattern and to produce a grid covering substantially any desired area.

7. As a new article of manufacture, a collapsible load-supporting structure forming, in expanded position, a structurally strong grid for spanning a predetermined area, said structure comprising at least four structurally strong trusses of substantially uniform construction interchangeable with one another and at least four connector members appreciably shorter in length than said trusses and of substantially uniform construction, said connector members also being interchangeable with one another, each connector member being pivotally mounted intermediate the ends of one of said trusses and being supported by said truss so that its ends extend on opposite sides of said truss and each of said trusses having one end thereof secured to one end of one of said connector members to form in expanded position a structural pattern whose center is a closed, foursided figure having its sides of equal length and formed by a portion of the length of each of said 1 four trusses, a connector member being located at each corner of said four-sided figure and a portion of each truss extending for a substantial part of its length as a projection of each side 0. said four-sided figure, one end of each of said connector members and of said trusses being thus available for further connection with other structurally strong trusses and connector members of similar construction to continue the foregoing structural pattern and to produce a grid covering substantially any desired area.

8. As a new article of manufacture, a collapsible load-supporting structure forming, in expanded position, a structurally strong grid for spanning a predetermined area, said structure comprising at least four structurally strong trusses of substantially uniform construction interchangeable with each other and at least four pairs of connector members, each of said connector members being appreciably shorter in length than said trusses and of substantially uniform construction, said connector members also being interchangeable with one another, each pair of connector members being pivotally mounted intermediate the ends of one of said trusses and being supported by said truss so that their ends extend on opposite sides of said truss and each of said trusses having one end thereof secured to one end of a pair of said connector members to form in expanded position a structural pattern whose center is a closed, four-sided figure having its sides of equal length and formed by a portion of the length of each of said trusses, a pair of connector members being located at each corner of said four-sided figure and a portion of each truss extending for a substantial part of its length as a projection of each side of said four-sided figure, one end of each pair of said connector members and of said trusses being available for further connection with other trusses and connector members of similar construction to continue the foregoing structural pattern and to produce a grid covering substantially any desired area.

9. As a new article of manufacture, a collapsible load-supporting structure forming, in expanded position, a structurally strong grid for spanning a predetermined area, said structure comprising at least four structurally strong trusses of substantially uniform construction interchangeable with one another and at least four connector members appreciably shorter in length than said trusses and of substantially uniform construction, said connector members also being interchangeable with one another, each connector member being pivotally mounted intermediate the ends of one of said trusses and being supported by said truss so that its ends extend on opposite sides of said truss and each of said trusses having one end thereof secured to one end of one of said connector members to form in expanded position a structural pattern Whose center is a closed, four-sided figure having its sides of equal length and formed by a portion of the length of each of said four trusses, a connector member being located at each corner of said four-sided figure and a portion of each truss extending for a substantial part of its length as a projection of each side of said foursided figure, one end of each of said connector members and of said trusses being thus available for further connection with other structurally strong trusses and connector members of similar construction to continue the foregoing structural pattern and to produce a grid covering substantially any desired area, one surface of each of said trusses lying in approximately the same plane as the corresponding surface of each of the other trusses, the structure being thus adapted to directly receive a suitable fiat covering for the area spanned thereby, the principal planar dimension 11 of said trusses being substantially perpendicular to the plane of the area spanned by said structure.

10. As a new article of manufacture, a collapsible load-supporting structure forming, in expanded position, a structurally strong grid for spanning a predetermined area, said structure comprising at least four structurally strong elements of substantially uniform construction interchangeable with one another and at least four connector members appreciably shorter in length than said elements and of substantially uniform construction, said connector members also being interchangeable with one another, each connector member being pivotally mounted intermediate the ends of one of said elements and being supported by said element so that its ends extend on opposite sides of said element and each of said elements having one end thereof secured to one end of one of said connector members to form in expanded position a structural pattern whose center is a closed four-sided figure having its sides of equal length and formed by a portion of the length of each of said four elements, a connector member being located at each corner of said fourslded figure and a portion of each element extending for a substantial part of its length as a projection of each side of said four-sided figure, one end of each of said connector members and of said elements being thus available for further connection with other structurally strong elements and connector members of similar construction to continue the foregoing structural pattern and to produce a grid covering substantially any desired area, each said element comprising a pair of beams spaced depthwise to provide a space for mounting the connector members associated with said element.

11. As a new article of manufacture, a collapsibl load-supporting structure forming, in expanded position, a structurally strong grid for spanning a predetermined area, said structure comprising at least four structurally strong trusses of substantially uniform construction interchangeable with one another and at least four 12 connector members appreciably shorter in lengt than said trusses and of substantially uniform construction, said connector members also being interchangeable with one another, each connector 5 member being pivotally mounted intermediate the ends of one of said trusses and being supported by said truss so that its ends extend on opposite sides of said truss and each of said trusses having one end thereof pivotally secured to one end of 10 one of said connector members to form in expanded position a structural pattern whose center is a closed, four-sided figure having its sides of equal length and formed by a portion of the length of each of said four trusses, a connector member 15 being located at each corner of said four-sided figure and a portion of each truss extending for a substantial part of its length as a projection of each side of said four-sided figure, one end of each of said connector members and of said trusses 2 being thus available for further connection with other structurally strong trusses and connector members of similar construction to continue the foregoing structural pattern and to produce a grid covering substantially any desired area.

25 ALFRED M. BUTTS.

REFERENCES CITED I The following references are of record in the file of this patent: 

